PRIMITIVE NERVE FIBRES AFTER SECTION. 
427 
The epithelium and the ciliary filaments are unaltered. 
On the seventh^ eighth and ninth days the disorganization of the nervous structure 
continues to progress. In the papillae the curdled particles of medulla become still 
more disconnected, and in parts are removed by absorption. The tubular sheath also 
is ruptured and disorganized near the extremities of the tubes. In the other ramifi- 
cations of the glossopharyngeal, the medulla becomes more and more disjointed and 
collected into oval or circular coagulated masses. 
On the tenth day and upwards we perceive another morphological state of the me- 
dulla. The coagulated particles lose their amorphous structure and assume a gra- 
nulated texture. The granules, retained together by slight cohesion, are dark by 
transmitted light, but of a light white colour by reflexion, and average i^^th of an 
inch. 
About the twentieth day the medullary particles are completely reduced to a gra- 
nular state. The condition of the papillary nerve is represented in Plate XXXI. fig. 2, 
where we find the presence of the nervous element merely indicated by numerous 
black granules, generally arranged in a row like the beads of a necklace. In their 
arrangement it is easy to detect the wavy direction characteristic of the nerves. They 
are still contained in the tubular membrane, which is but very faintly distinguished, 
probably from the loss of the medulla and from atrophy of its tissue. The resistance 
of these granular bodies to chemical agents is most remarkable, for they remain un- 
affected by acids, alkalies and the ethers, which have so great an influence over the 
nervous medulla. These granules may be detected within the papillary nerves for a 
considerable period of time. I have seen them apparently unaltered in the papillae 
upwards of five months after division of the nerve, reunion not having taken place. 
Division of the Hypoglossal Nerve. 
When the hypoglossal nerves are divided at their exit from the spine, all move- 
ments of the throat and tongue are abolished, and the process of respiration entirely 
at an end. The tongue may be drawn from the mouth remaining completely inert, 
pinching or cutting causing no appearance of pain. Hence we may conclude that 
this nerve is of a mixed nature, containing sensorial as well as motor filaments. An- 
other experiment, which shows this more plainly, consists in dividing one hypoglossal 
nerve near the spine on one side, and on the other the glossopharyngeal at its exit 
from the cranium. Pinching and other modes of irritation cause no pain on the side 
where the hypoglossal is divided, while on the other undoubted pain is caused. 
After division of the hypoglossals at the throat, the motor and sensorial powers of 
the tongue are not entirely lost. When drawn out of the mouth, the extremity only re- 
mains fixed between the jaws, flaccid and powerless. At the inner half the fibres are 
still contractile, on account of their belonging to the hypoglossus, which at its lower 
half receives a branch from the hypoglossal nerve above the point of section. By this 
3 I 2 
